Orifice plates for the dry, wet, or underwater pelletizing process for plastic strands from the melt are attached directly to the extruder apparatus and are subjected to high loads and wear. Consequently, most orifice plates consist of a base plate provided with melt inlet channels and wear-resistant hardenable inserts, in which bores are provided for melt discharge. These inserts are generally soldered in corresponding recesses in the base plate.
At present, these inserts are soldered into the base plate and then must be brought to an operational state by means of a corresponding heat treatment prior to the formation of the bores for melt discharge. After forming the bores for melt discharge a further heat treatment for hardening the insert is necessary.
These two heat treatments are expensive and in addition to them there is the great disadvantage that in order to drill the bores for melt discharge in the inserts, large processing units are required for relatively large orifice plates. Particular difficulties are encountered in forming melt discharge bores which extend at an angle relative to the longitudinal axis of the melt inlet channels in the base plate, as shown, for example, in DE 38 09 735.